The present disclosure of this application relates to the removal or inactivation of hydrogen sulfide or other species comprising ionizable sulfur (e.g., mercaptans, thiols, etc.) which may be encountered in wells which penetrate subterranean formations such as oil wells, gas wells and the like. Fluids in sewage systems, fluids produced from wells and make-up fluids also frequently contain hydrogen sulfide. Hydrogen sulfide gas is toxic with a density heavier than air, and therefore removal or inactivation of this sulfide ion is necessary to prevent poisoning of surrounding personnel and contamination of the area. Moreover, hydrogen sulfide gas is highly corrosive to the pipeline and equipment used in the operation of an oil well. Therefore, removing hydrogen sulfide from produced fluid (i.e., oil and water) and gas is necessary for the safe production of oil.
Drilling a well in a hydrocarbon bearing subterranean formation for the production of hydrocarbons from said formation typically involves use of a drilling apparatus and drilling fluid. The drilling apparatus usually comprises a bit mounted on a string of hollow steel pipe. This hollow pipe is often used to rotate the bit to enable the bit to cut into the formation. The hollow pipe also acts as a conduit for the drilling fluid to be pumped down to the bottom of the hole, from where it rises to the surface via the annulus between the drill string and the borehole wall. The drilling fluid has many functions, one of the most important of which is to convey the cuttings from the bit downhole up to the surface of the well.
In drilling some subterranean formations, and often particularly those bearing oil or gas, hydrogen sulfide accumulations are frequently encountered. The drilling fluid brings the hydrogen sulfide to the surface. Such sulfide in the drilling fluid is problematic because it can corrode the steel in the drilling apparatus and may be liberated into the atmosphere as toxic sulfide gas at the well surface.
Generally, to protect the health of those working with the drilling fluid and those at the surface of the well, conditions should be maintained to ensure that the concentration of hydrogen sulfide above the fluid, emitted due to the partial pressure of the gas, is less than about 15 ppm.
Triazine-based hydrogen sulfide scavengers have been commonly used in the oil and gas industry, but triazine can increase pH values of produced water and cause scale problems. Acrolein is another common hydrogen sulfide scavenger because it can react with hydrogen sulfide at a fast rate. However, acrolein is highly reactive and toxic, which may create added difficulties for transportation, storage, and operation.
While embodiments of this disclosure have been depicted and described and are defined by reference to example embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.